How to get result from BridgeTalk message?

Hi Bob,

Thank you so much for the quick reply and intelligible explanation. You opened my eyes to this problem. I reached a deadlock and you showed me the way out of it. I wouldn't be able to solve this thing without your help. Now it works at last!
Thank you again, Bob.

Kasyan

#target indesign-5.0

#targetengine "session"



function infoFromPS() {

   var bt = new BridgeTalk;

   bt.target = "photoshop";

   bt.body = "app.colorSettings;"

   bt.onResult = function(resObj) {

      var myResult = resObj.body;

      $.writeln( "BridgeTalk result = " + myResult );

      doSomethingNow( myResult );

   }

   bt.send();

}



function doSomethingNow( result ) {

   if (result != "ISO Web Coated") {

      alert( "Color Settings in Photoshop are set to \"" + result + "\"");

   }

}



infoFromPS();

Your questions tell me that you don't really understand the asynchronous behavior or BridgeTalk.

When you call bt.send() to send your BridgeTalk message, your script doesn't stop. I continues to execute until completion. Your onResult handler function is called when a result is received from the target application.

Without a persistent session, InDesign (and PS) start a scripting engine for your script. When your script completes, the scripting engine is killed off.

If you send a BridgeTalk message in such a script, when the result comes back to InDesign, the reference to your script and its scripting engine no longer exists. That's why you MUST use a persistent session in InDesign if you are sending a BridgeTalk message and expecting a response.

In the code you provided, think of the onResult handler as a separate function to be executed at some future time.

Your function infoFromPS() does not return anything, which is why the first writeln returns "undefined".

Your onResult function will execute when a result is received; but, that will be at some future time, long after your infoFromPS() function has already returned.

The execution works like so:

var myResult2 = infoFromPS();
- this causes the infoFromPS() function to execute...

infofromPS() creates a BT message, sets the properties including the onResult handler, and calls "bt.send()". It then completes, and returns nothing (undefined).

The next line to execute (because infoFromPS() has compelted) is:

$.writeln("myResult2 = " + myResult2);

And since infoFromPS() returned noting, you get

myResult = undefined

in the ESTK.

Then, at some time (depends on how long the script takes to execute in Photoshop - could be hours), a response message is received from Photoshop. At that time, your onResult handler executes:

myResult1 is set to the response message body, the $.writeln writes the correct stuff into the ESTK console, and the onResult function returns myResult1 (which does nothing). You can't "return" something from an onResult handler.

The correct way to use BridgeTalk is to write your script so that it sends the message, and then to write the onResult handler so it does what you need with the returning message.

#target indesign;
#targetengine "session"

function infoFromPS() {
var bt = new BridgeTalk();
bt.target = "photoshop";
bt.body = "app.colorSettings;"
bt.onResult = function( msg ) {
var myResult = msg.body;
$.writeln( "BridgeTalk result = " + myResult );
doSomethingNow( myResult );
}
bt.send();
}

doSomethingNow = function( result ) {
$.writeln( "Now I am doing something with " + result );
}

infoFromPS();

This *should* (I haven't tested it) write into the ESTK console:

"BridgeTalk result..."
"Now I am doing something with..."

Regards

Bob